The speaker module is an important acoustic component of a portable electronic device for converting between an electrical signal and a sound signal, and is an energy conversion device. The existing speaker module generally comprises a module housing and a speaker unit, wherein the module housing forms a module cavity for accommodating the speaker unit therein, and the speaker unit separates the module cavity into a front acoustic cavity and a rear acoustic cavity, and a sound-absorbing component made of a sound absorbing material such as sound absorbing cotton may be disposed in the rear acoustic cavity to adjust the acoustic performance of the module.
In recent years, with the increasing thinness and lightness of wearable electronic products, the sound-absorbing components made of conventional sound absorbing materials have been unable to meet the debugging and calibration requirements of the acoustic performance in the micro speaker industry. In order to solve this problem, new sound absorbing materials are constantly being developed and experimented, and it has been verified that the acoustic performance can be effectively improved by placing porous sound absorbing materials in the rear acoustic cavity of the speaker module. At present, such new sound absorbing materials with good application effects include non-foaming sound absorbing materials such as natural zeolite, activated carbon, white carbon black, silicon dioxide, artificial zeolite, or a mixture of the above two or more materials. When the above-described non-foaming sound absorbing material is applied to the speaker, the above powdery non-foaming sound absorbing material is required to be firstly prepared into sound-absorbing particles having a particle diameter of 0.1 to 1.0 mm for the quantifiability and process filling practicability. According to the size configuration of the rear acoustic cavity of the speaker products, the particle size of the sound-absorbing particles of the non-foaming sound absorbing materials can be selected within a range of 0.1 to 1.0 mm.
At present, the following three methods are generally adopted to manufacture the sound-absorbing component by using the above-mentioned non-foaming sound absorbing materials in the speaker industry.
1. Referring to FIG. 1, a plastic or metal mesh such as PP, PC, PE and the like is formed into a bracket shell 11′ that is adapted to the rear acoustic cavity of the speaker module, and then the sound-absorbing particles 13′ are loaded into the bracket shell, and finally the bracket shell is packaged with the shell cover 12′ by means of gluing, hot-pressing or the like, and the shell cover 12′ may be packaged by non-woven fabrics, a Mesh-mesh or a metal mesh, so that the sound-absorbing component is formed;
2. The wire mesh cloth made of PP, PE, etc. is made into a cloth bag by means of gluing, hot-pressing, etc., and then the sound-absorbing particles are placed into the cloth bag, and finally, the package is completed using methods such as gluing and hot-pressing, then the sound-absorbing component is formed;
3. An independent ventilating cavity is constructed in the rear acoustic cavity of the speaker module by a wire mesh cloth, a metal mesh or the like added in the housing of the speaker module in combination with the housing of the speaker module, and then a filling hole is reserved on the independent ventilating cavity in advance to complete the direct filling of the non-foaming sound absorbing material particles, thereby forming the sound-absorbing component.
Since the non-foaming sound absorbing material itself is a porous material and has a high specific surface area, therefore static electricity is easily generated when the non-foaming sound absorbing material comes into contact with air, moreover, the non-foaming sound absorbing material is an insulator, which causes the electric charge to continuously accumulate and the electrostatic effect to continuously enhance. In addition, the porous non-foaming sound absorbing material itself has polar defect point and will be charged itself. Due to the above-described reasons, the electrostatic problem in the filling of the non-foaming sound absorbing material particles occurs, which results in the following adverse effects:
1. In the filling process of the above three application forms of making the sound-absorbing component using the non-foaming sound absorbing material particles, the non-foaming sound absorbing material particles cannot completely fill the predetermined filling area due to the electrostatic repulsion effect between the particles, and the filling amount is small with the fill rate of about 55% to 75%, so that it is difficult to effectively utilize the space of the rear acoustic cavity of the speaker, and the improvement effect on the acoustic performance of the speaker is significantly restrained;
2. Since the non-foaming sound absorbing material particles are prone to generate static electricity, when the particles are packaged to form a sound-absorbing component after filling, a certain number of particles may enter into the package area, causing failure of the packaging operation and low package yield, or affecting the package strength, and, the package is easily damaged in the working process of the speaker module due to factors such as aging and external forces, resulting in leakage of sound-absorbing particles and thereby affecting the acoustic quality of the speaker.